Removable cassette for 3D printers

ABSTRACT

In example implementations, an apparatus includes a housing, a movable base, a tab portion and a coupling mechanism. The housing is comprised of a microwave transparent material. The movable base is coupled to the housing to receive build material that is digitally printed. The tab portion is coupled to a bottom portion of at least one wall of the housing. The tab portion stops the movable base. The coupling mechanism is coupled to the housing to removably attach the apparatus to a three dimensional printer.

BACKGROUND

Three dimensional (3D) printers are becoming more ubiquitous as costsfor the printers come down. 3D printers, also referred to as additivemanufacturing machines, typically operate by using a material togenerate a 3D object layer-by-layer. In some systems, a threedimensional computer aided drawing (CAD) model may be created. Then, anobject may be generated in accordance with the model. Example materialsmay include polymers, metals, or plastic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an example apparatus of the presentdisclosure;

FIG. 2 is an example of a cross-sectional side view of a removablecassette of the present disclosure;

FIG. 3 is an example bottom view of the removable cassette of thepresent disclosure;

FIG. 4 is an example schematic flow diagram of the present disclosure;

FIG. 5 is a flow diagram of an example method for using a removablecassette for 3D printing; and

FIG. 6 is a block diagram of an example controller of the presentdisclosure.

DETAILED DESCRIPTION

The present disclosure discloses an apparatus and method for using aremovable cassette for 3D printing. The removable cassette may beattached to a 3D printer. Layers of build material may be dispensed ontoa movable base plate. In the present example, portions of each layer ofbuild material may be digitally printed with a liquid functionalmaterial within the removable cassette. The liquid functional material“outlines” the portions of each layer that will form the threedimensional object after the build material is fused. Notably, in thepresent disclosure, each layer is not cured or fused after applicationof the liquid functional material to portions of each layer of the buildmaterial.

Rather, after portions of each layer of build material are digitallyprinted, the removable cassette may be covered with a lid and moved to afurnace to fuse the digitally printed portions of each layer of buildmaterial. In other words, the fusing of digitally printed layers of thebuild material occurs in the furnace, rather than within the 3D printeras with some other 3D printing techniques.

In contrast, a typical 3D printing process heats and fuses each layer aseach layer is being printed or immediately after each printing pass of alayer. By eliminating the heating process during or after each layer isprinted, the efficiency of the 3D printing process and uniformity ofmaterial properties may be improved. Rather, the present disclosureallows layers of build material that are digitally printed, but unbound,to be placed into the removable cassette and placed into a furnace(e.g., a microwave furnace, a furnace, a fusing chamber exposing theobjects to electromagnetic radiation outside the range designated asmicrowave radiation). The furnace provides heat or energy that fuses theportions of the build material that received the liquid functionalmaterial to each other and between layers of the build material thatreceived the liquid functional material. The portions of each layer ofthe layers of build material that are digitally printed with the liquidfunctional material may be fused simultaneously, or at the same time,within the removable cassette in a single step.

FIG. 1 illustrates a block diagram of an example 3D printer 100 of thepresent disclosure. In one example, the 3D printer 100 may include aremovable cassette 120, a liquid functional material (LFM) dispenser 110and a build material dispenser and spreader 112. In one implementation,a movable base 122 of the removable cassette may be coupled to a motor116 to move the movable base 122 up and down.

In one implementation, a controller 114 may be in communication with theLFM dispenser 110, the build material dispenser and spreader 112 and themotor 116. The controller 114 may control the build material dispenserand spreader 112 to dispense layers 104-1 to 104-N (herein referred toindividually as a layer 104 or collectively as layers 104) of a buildmaterial 102. The controller 114 may control the LFM dispenser 110 todispense LFM on portions of each layer 104 of build material 102. Thecontroller 114 may control the motor 116 to move the movable base 122lower after each layer 104 is provided and digitally printed by the LFMto receive an additional layer 104 of build material 102.

In one example, the movable base 122 may be coupled to the motor 116 viaan interface. For example, the interface may be a mechanical connection.For example, the movable base 122 may be coupled to the interface thatcomprises a lead screw that is connected to the motor 116. The motor 116may be a stepper motor that moves the lead screw in defined increments.The movement of the movable base 122 in a downward direction may bereferred to as indexing down and the movement of the movable base 122 inan upward direction may be referred to as indexing up.

In one example, a structure 106 may be designed using, for example, acomputer aided design (CAD) program and uploaded to the controller 114.In some implementations, bitmap slices of each layer or raster slices ofeach layer of a design of the structure 106 may be uploaded to thecontroller 114. The controller 114 may then control the LFM dispenser110, the build material dispenser and spreader 112 and the motor 116 todigitally print the structure 106 in the layers 104 of the buildmaterial 102 without applying energy between each one of the layers 104of build material 102 that is dispensed.

In one implementation, the build material 102 may be a microwavetransparent material. The microwave transparent material may be any typeof granular material including a powder, a gel, a slurry, and the like,that is predominately microwave transparent. The granular material mayhave an average diameter of approximately 3-30 microns (μm). Forslurries and gels, the average diameter may be as small as 1 nanometer(nm). Examples of microwave transparent materials that can be used asthe build material 102 may include alumina (Al₂O₃), silicon nitride(SiN), a ceramic, a glass ceramic, a glass, polytetrafluoroethylene(PTFE), zirconium dioxide (ZrO₂), silicon dioxide (SiO₂), yttrium oxide(Y₂O₃), magnesium oxide (MgO), aluminum oxide (Al₂O₃), boron nitride(BN), calcium fluoride (CaF₂), tantalum pentoxide (Ta₂O₅), niobiumpentoxide (Nb₂O₅), titanium oxide (TiO₂), quartz, fused silica, mullite,and the like.

A layer 104 of the build material 102 may be dispensed onto the movablebase 122 and rolled to be level, or even, by the build materialdispenser and spreader 112. Based on the structure 106, the controller114 may dispense LFM onto portions of the layer 104 of build material102. The LFM may be a susceptor that absorbs microwave energyselectively better than the build material 102. The LFM may also be amaterial designed to decrease the local fusing temperature or otherwiselocally modify the material properties of the digitally defined object.The layer 104 of the build material 102 is digitally printed by applyingthe LFM to the portions of the layer 104 of the build material 102 tocreate a susceptor pattern that corresponds to a respective layer of thestructure 106. The LFMs may also be used to modify the local electricalor other fundamental properties of the build material 102 to create abenefit to the final structure 106.

It should be noted that the LFM is not a binder by itself and does notbind the particles of the build material 102 without application ofenergy. In other words, the LFM alone does not bind the particles of thebuild material 102. Rather an energy is applied to the LFM in a furnace,as described below to bind the build material 102.

An example of the LFM may include any type of material that isconducting, semi-conducting or have a magnetic dipole that can be usedas microwave, or radio frequency (RF) susceptors at ambient temperature.Some examples may include carbon black, graphite, carbon nano tubes,silicon carbide (SiC), zinc oxide (ZnO), indium tin oxide (ITO),titanium nitride (TiN), ferrite inks, ferromagnetic materials,ferroelectric materials, and the like.

In addition, the LFMs may include materials designed to react with abase material to enable fusing with less fusing energy delivered. Thismay include silicon oxide (SiO₂) nano-particles, combinations of oxidesto form glass in the interstitial regions between particles, and thelike.

The dispensing of the build material 102 and the digital printing ofportions of the layer 104 of the build material 102 may be repeateduntil the entire structure 106 is digitally printed within a pluralityof layers 104-N of the build material 102. Notably, each layer 104 ofthe build material 102 is not heated or fused. Rather, the layers 104-1to 104-N of the build material 102 remain loose, unbound or uncured.

In one implementation, additional layers 104 that are free from the LFMmay be dispensed as a bottom most layer and a top most layer to provideinsulation. In addition, the structure 106 may be digitally printedwithin each layer 104 of the build material 102 at a minimum distance118 from walls 150 of the removable cassette 120 to provide aninsulation layer. In one implementation, the minimum distance 118 may beapproximately greater than or equal to 10 millimeters (mm).

As discussed below, the layers 104-1 to 104-N of the build material 102may be inserted into the removable cassette 120. The removable cassette120 can be removed from the 3D printer 100 and inserted into a furnace(e.g., a microwave furnace, a furnace, a fusing chamber exposing theobjects to electromagnetic radiation outside the range designated asmicrowave radiation) to fuse the digitally printed portions of eachlayer 104-1 to 104-N at the same time.

In one implementation, the removable cassette 120 may include at leastone tab portion 130. The tab portion 130 may be any shape and locatednear a bottom edge of the removable cassette 120. The tab portion 130may provide a stopping location for the movable base 122. The tabportion 130 may be integrally formed as part of the removable cassette120 (e.g., the tab portion 130 and the removable cassette 120 are asingle unitary piece). Alternatively, the tab portion 130 may beseparately coupled to the removable cassette 120 as a separate piece.

In one implementation, the removable cassette 120 may also include atleast one mechanical feature 132 to couple the removable cassette 120 tothe 3D printer 100. For example, a platform or a bed 140 of the 3Dprinter 100 may include a fastener, a spring loaded clamp, a slot, andthe like that can mate with, or lock onto, the mechanical feature 132 tohold the removable cassette 120 stable and in position while the layers104 of the build material 102 are dispensed and the portions of thelayers 104 of the build material 102 are digitally printed.

FIG. 2 illustrates an example cross-sectional side view of the removablecassette 120 that is insertable into the 3D printer 100. FIG. 2illustrates the movable base 122, the tab portion 130 and the mechanicalfeature 132, as described above. In one example, the movable base 122may be fabricated from a reflective metal or a microwave transparentmaterial. For example, the movable base 122 may be a microwavetransparent material when the removable cassette 120 is inserted into acompleted microwave cavity. The movable base 122 may be made of, or maycomprise, a reflective material when a base of the removable cassette120 is designed to be an active part of the microwave cavity.

In one implementation, the movable base 122 may fit within a housing 138formed by walls 150 such that the build material 102 does not leak orfall out of the movable base 122. In other words, the movable base 122may be sealed or tightly fit within the walls 150 of the housing 138such that the build material 102 does not leak out between the movablebase 122 and the walls 150.

In one implementation, the removable cassette 120 may also include amovable lid 134. The movable lid 134 may be in an open position duringdispensing of the build material 102 into the removable cassette 102 andin a closed position during transportation of the layers 104 of thebuild material 102.

In one example, the walls 150 of the housing 138 and the movable lid 134may be fabricated from a microwave transparent material. As discussedabove, examples of microwave transparent materials may include alumina(Al₂O₃), silicon nitride (SiN), a ceramic, a glass ceramic, a glass,polytetrafluoroethylene (PTFE), zirconium dioxide (ZrO₂), silicondioxide (SiO₂), yttrium oxide (Y₂O₃), magnesium oxide (MgO), aluminumoxide (Al₂O₃), boron nitride (BN), calcium fluoride (CaF₂), tantalumpentoxide (Ta₂O₅), niobium pentoxide (Nb₂O₅), titanium oxide (TiO₂),quartz, fused silica, mullite, and the like.

FIG. 3 illustrates an example bottom view of the removable cassette 120.The movable base 122 may include an opening 136. The opening 136 may bethreaded or smooth to connect to a mechanical device of the 3D printer100 to move the movable base 122. For example, as described above, themechanical device may be a lead screw that is connected to the opening136 and coupled to the motor 116.

The bottom view in FIG. 3 illustrates the four walls 150 of the housing138 in a square or a rectangular shape. However, it should be noted thatthe removable cassette 120 may have any shape for a particularapplication.

FIG. 3 illustrates an example of the tab portions 130 as being arectangular shape on opposite sides of a bottom portion of the housing138. However, it should be noted that the tab portions 130 may be anysize or any number. For example, the tab portions 130 may be smallersquares located in each corner of the housing 138, may be smallersquares located in the middle bottom edge of each wall 150, and thelike.

FIG. 3 also illustrates an example of the mechanical feature 132.Although the mechanical feature 132 is illustrated on two opposite walls150, it should be noted that the mechanical feature 132 may be locatedon wall 150. In addition, the removable cassette 120 may have any numberof mechanical features 132. Furthermore, although the mechanical feature132 is illustrated as running along an entire width of the wall 150, itshould be noted that the mechanical feature 132 may be smaller andlocated anywhere along the width of the wall 150.

FIG. 4 illustrates an example schematic flow diagram of a method forusing a removable cassette for 3D printing. At block 402, a layer 104-1of build material 102 may be dispensed onto the movable base 122 of theremovable cassette 120. The removable cassette 120 may be removablycoupled to the 3D printer 100 via the mechanical features 132.

At block 404, the LFM may be dispensed onto selective portions of thelayer 104-1 of the build material 102. After the LFM is dispensed, themovable base 122 may be indexed down and return to block 402 to receiveanother layer 104-2 of building material 102. The blocks 402 and 404 maybe repeated until an entire structure 106 is digitally printed intolayers 104-1 to 104-N of the build material 102 as shown in block 406.

After the structure 106 is defined by the digitally printed portions ofthe layers 104 of build material 102, the movable lid 134 may be movedinto a closed position. After the movable lid 134 is closed, the layers104 of build material 102 may be secured in the removable cassette 120and safely transported.

In one implementation, a filler material may also be inserted into theselected portions of the layer 104-1 of the build material 102. Thefiller material may be used to increase the density of the buildmaterial 102 or to help drive the fusing process (discussed below).Examples of filler material that may be used may include nano-particlesof ceramics, Sol-Gel, and the like.

At block 408, the removable cassette 120 may be removed from the 3Dprinter 100. The removable cassette 120 may be designed to ensure thatthe layers 104-1 to 104-N remain stable inside the removable cassette120. As noted above, each layer 104-1 to 104-N is not fused afterportions of each layer 104 are digitally printed. Said another way, thelayers 104-1 to 104-N remain unbound, unfused, or uncured whentransported in the removable cassette 120.

At block 410, the removable cassette 120 may be inserted into a furnace124. The furnace 124 may be a microwave furnace. The furnace may fusethe portions of each layer 104 that were digitally printed with the LFMat the same time. As noted above, the LFM may be a susceptor thatabsorbs microwave energy selectively better than the surrounding buildmaterial 102 that does not receive the LFM. As a result, the definedstructure 106 may be fused as illustrated in block 410 without thedashed lines of each layer 104. In one example, the excess buildmaterial 102 that is not fused may be removed and recycled. Theremovable cassette 120 may also be reused.

FIG. 5 illustrates a flow diagram of an example method 500 for using aremovable cassette for 3D printing. In one example, the blocks of themethod 500 may be performed by the controller 114 or using the 3Dprinter 100.

At block 502, the method 500 begins. At block 504, the method 500provides a layer of build material into a removable cassette. In oneexample, the build material may be a microwave transparent material. Themicrowave transparent material may be a powder that is microwavetransparent. The particles of powder may have an average diameter ofapproximately 3-30 microns (μm). Examples of microwave transparentmaterials that can be used as the build material may include alumina,silicon nitride, a ceramic, a glass ceramic, a glass,polytetrafluoroethylene (PTFE), zirconium dioxide (ZrO₂), silicondioxide (SiO₂), yttrium oxide (Y₂O₃), magnesium oxide (MgO), aluminumoxide (Al₂O₃), boron nitride (BN), calcium fluoride (CaF₂), tantalumpentoxide (Ta₂O₅), niobium pentoxide (Nb₂O₅), titanium oxide (TiO₂),quartz, fused silica, mullite, and the like.

The removable cassette may be coupled to a platform or a bed of the 3Dprinter via a mechanical feature of the removable cassette. A base plateof the removable cassette may be indexed up and down via a mechanicaldevice. For example, a lead screw may be coupled to an opening on abottom side of the base plate and the lead screw may be coupled to astepper motor.

At block 506, the method 500 digitally prints a liquid functionalmaterial (LFM) on portions of the layer of build material in theremovable cassette. For example, a LFM may be dispensed onto theportions of the layer of build material that will define a structure.The LFM may be a susceptor that absorbs microwave energy selectivelybetter than the build material. The LFM may be applied to the portionsof layer of build material to create a susceptor pattern thatcorresponds to a respective layer of the structure 106.

At block 508, the method 500 repeats the providing and the digitallyprinting without applying energy to the LFM to define a structure inlayers of build material in the removable cassette. For example, thestructure may be defined or digitally printed layer by layer. In otherwords, a layer of build material may be added, portions of the layer ofbuild material may be digitally printed by applying the LFM to theselect portions, another layer of build material may be added on top ofthe previous layer of build material, portions of the new layer of buildmaterial may be digitally printed, and so forth, until enough layers ofbuild material are digitally printed to define the structure.

At block 510, the method 500 removes the removable cassette from a 3Dprinter. For example, a movable lid of the removable cassette may bemoved to a closed position to seal the removable cassette. Themechanical features may be uncoupled from the platform or the bed of the3D printer.

At block 512, the method 500 places the removable cassette containingthe layers of the build material that are uncured into a furnace.Notably, the removable cassette may contain the layers of build materialthat are digitally printed, but unbound. In addition, the removablecassette may be designed to provide stable transportation of the layersof build material. In other words, the layers of the build material maynot move significantly within the removable cassette duringtransportation.

At block 514, the method 500 fuses the portions of the layers of buildmaterial that are digitally printed to form the structure in theremovable cassette. For example, the portions of the layers of buildmaterial that are digitally printed may be heated or fusedsimultaneously, or at the same time. In other words, rather than fusingportions of each layer of the build material after each pass, thepresent disclosure may fuse each layer of build material that isdigitally printed simultaneously, or at the same time, inside thefurnace and within the removable cassette. At block 516, the method 500ends.

FIG. 6 illustrates another example of an apparatus 600. In one example,the apparatus 600 may also be the controller 114. In one example, theapparatus 600 may include a processor 602 and a non-transitory computerreadable storage medium 604. The non-transitory computer readablestorage medium 604 may include instructions 606, 608 and 610 that whenexecuted by the processor 602, cause the processor 602 to performvarious functions.

In one example, the instructions 606 may include instructions todispense a layer of build material in a removable cassette. Theinstructions 608 may include instructions to dispense LFM onto portionsof the layer of build material in the removable cassette. Theinstructions 610 may include instructions to repeat the instructions todispense the layer of build material and the LFM to define a structurein layers of build material in the removable cassette.

It will be appreciated that variants of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be combined intomany other different systems or applications. Various presentlyunforeseen or unanticipated alternatives, modifications, variations, orimprovements therein may be subsequently made by those skilled in theart which are also intended to be encompassed by the following claims.

The invention claimed is:
 1. An additive manufacturing system,comprising: a three-dimensional printer comprising: a removable cassetteto receive a number of stacked layers of build material; a buildmaterial dispenser and spreader to form each layer of build material inthe removable cassette; a liquid functional material (LFM) dispenser todigitally print LFM on portions of each layer of build material in theremovable cassette; and a controller programmed to control the buildmaterial dispenser and spreader and the LFM dispenser to repeatedly formlayers of build material and digitally print LFM into portions of eachlayer without applying energy to the LFM to define a structure in layersof build material in the removable cassette; and a separate furnace toreceive the removable cassette when the removable cassette is removedfrom the three-dimensional printer, the furnace for curing the portionsof the layers of build material that are digitally printed with LFM toform a specified object in the removable cassette.
 2. The system ofclaim 1, wherein the furnace comprises a heater to apply heat to curethe build material printed with LFM.
 3. The system of claim 1, wherein:the removable cassette comprises a housing defining an interior spacewhere an object is formed from the layers of build material, the housingbeing comprised of a microwave transparent material, the microwavetransparent material arranged so as to admit microwave radiation from anexterior of the housing into the interior space where an object isformed; and the furnace is a microwave furnace.
 4. The system of claim1, wherein the removable cassette comprises: a movable base within ahousing, the movable base to receive the layers of build material; and atab portion coupled to a bottom portion of at least one wall of thehousing, wherein the tab portion stops the movable base.
 5. The systemof claim 4, wherein the movable base indexes up and down within thehousing, the movable base tightly abutting sidewalls of the housing witha sealed fit to prevent build material leaking between the movable baseand sidewalls of the housing.
 6. The system of claim 4, wherein themovable base comprises a reflective metal.
 7. The system of claim 4,wherein the movable base comprises a microwave transparent material. 8.The system of claim 7, wherein the microwave transparent materialcomprises at least one of: alumina (Al₂O₃), silicon nitride (SiN), aceramic, a glass ceramic, a glass, zirconium dioxide (ZrO₂), silicondioxide (SiO₂), yttrium oxide (Y₂O₃), magnesium oxide (MgO), aluminumoxide (Al₂O₃), boron nitride (BN), calcium fluoride (CaF₂), tantalumpentoxide (Ta₂O₅), niobium pentoxide (Nb₂O₅), titanium oxide (TiO₂),quartz, fused silica or mullite.
 9. The system of claim 1, wherein theremovable cassette comprises: a housing defining an interior space wherean object is formed from the layers of build material; and a couplingmechanism coupled to the housing to removably attach the removablecassette to the three-dimensional printer.
 10. The system of claim 9,comprising: a movable lid coupled with a hinge to a top portion of thehousing so as to pivot about the hinge to cover the layers of buildmaterial in the housing after portions of each one of the layers ofbuild material are digitally printed to define the specified object. 11.The system of claim 9, wherein the coupling mechanism comprises arotating lead screw coupled to a stepper motor.
 12. The system of claim1, further comprising a supply of LFM for the LFM dispenser.
 13. Thesystem of claim 12, wherein the LFM lowers a local curing temperature ofbuild material that receives the LFM to facilitate curing of the buildmaterial that has received the LFM when processed in the furnace. 14.The system of claim 12, wherein the LFM is a susceptor that absorbsradio frequency energy to cure build material in which the LFM has beenapplied.
 15. The system of claim 1, wherein the controller operates theLFM dispenser so that build material at a bottom, sides and top of theremovable cassette is not treated with the LFM to provide insulationaround the specified object being formed in the layers of buildmaterial.
 16. An additive manufacturing system, comprising: athree-dimensional printer comprising: a removable cassette to receive anumber of stacked layers of build material; a build material dispenserand spreader to form each layer of build material in the removablecassette; a liquid functional material (LFM) dispenser to digitallyprint LFM on portions of each layer of build material in the removablecassette; and a controller programmed to control the build materialdispenser and spreader and the LFM dispenser to repeatedly form a layerof build material and digitally print LFM into portions of that layer toform the number of stacked layers of build material, the controller toform the number of stacked layers without applying a curing energy tothe LFM, wherein the three-dimensional printer lacks an energy source tocure build material that has received LFM; and a separate furnace toreceive the removable cassette when the removable cassette is removedfrom the three-dimensional printer, the furnace to apply heat or energyto the stacked layers of build material for curing the portions of thelayers of build material that are digitally printed with LFM to form aspecified object in the removable cassette.
 17. The system of claim 16,wherein the furnace comprises a heater to apply heat to cure the buildmaterial printed with LFM.
 18. The system of claim 16, wherein theremovable cassette comprises: a movable base within a housing, themovable base to receive the layers of build material, wherein themovable base comprises a microwave transparent material or a reflectivemetal; and a tab portion coupled to a bottom portion of at least onewall of the housing, wherein the tab portion stops the movable base. 19.The system of claim 18, wherein the movable base comprises a reflectivemetal.
 20. The system of claim 16, wherein the controller operates theLFM dispenser so that build material at a bottom, sides and top of theremovable cassette is not treated with the LFM to provide insulationaround the specified being formed in the layers of build material.